The present invention relates to device for controlling electric motor-reduction units of the type intended for driving the winding rod, drum or tubular core of a rolling shutter, roller-blind or the like, which comprises a plurality of cams disposed side by side on a common shaft about which they can pivot freely, the outer operative contour of each cam comprising only a single notch. All the cam notches are adapted to be engaged simultaneously by a member controlling a motor control switch, this control member being constantly urged by at least one suitable resilient means against the outer contours of said notched cams, said cams being rigidly coupled with toothed wheels disposed laterally and coaxially in relation thereto and in constant meshing engagement with toothed driving pinions disposed on a shaft parallel to the cam shaft, so as to drive said cams at rotational speeds differing from one cam to another.
A device is provided for aligning at will the cam notches with the switch control member. This device comprises heart-shaped cams each rigid with one of the side faces of a notched cam, and said heart-shaped cams being adapted to cooperate with an aligning member. A control member movable across the cam axis is adapted in a first time period to cooperate with one portion of the switch control member in order to move said switch control member away from the notched cam contours, against the force of the resilient means of said member; in a second time period, said control member is adapted to move the shaft of the toothed drive pinions away from the cam shaft while a resilient means positions and aligns the toothed pinion teeth with respect to the teeth of the matching toothed wheels registering therewith, and in a third time period the same control member is adapted to cause the set of heart-shaped cams to cooperate with the aligning means.
In known devices of this character, such as the one shown diagrammatically in FIG. 1 of the attached drawing, the shaft 1 of the toothed drive pinions 2 is supported by a slide 3 movable in the direction of the arrow 4 against the force of a spring 5 which on the other hand and simultaneously urges the operative beaks 8 of the pivoted lever 6 controlling the motor switch 7 against the outer periphery of notched cams 9. However, this device is attended by various inconveniences; in fact, since the toothed drive pinions are radially movable, the kinematic linkage between the motor-reduction unit and these drive pinions is relatively complicated, inasmuch when this motor-reduction unit has to be coupled in certain cases to two such control devices for stopping the rolling shutter, roller blind or the like in its closed (wound-up) or open (unrolled) positions, respectively. Moreover, the spring 5 must be relatively strong, otherwise the effort exerted by the toothed pinions 2 for rotatably driving the cams 9 might eventually move the toothed pinions 2 in direction 4 and thus disengage them from their meshing engagement with toothed wheels 9, thus discontinuing the drive of these toothed wheels 9. This driving effort is particularly high when the cams 9 must expel from their notches 8 the beaks of member 6 controlling switch 7, against the force of spring 5. Moreover, due to this substantial stressing of spring 5, a considerable effort must be exerted in the direction 4 when it is desired to actuate the device voluntarily for aligning the notches 8 with respect to the beaks of the switch control member 6.